Articles

  1. INVESTIGATION OF STRESS REDUCTION EFFECT ON STRUCTURES DUE TO BASEMAT UPLIFT USING ENERGY CONCEPT Download Article

    Takafumi Inoue and Atsushi Mikami
    • Article Type: Research Article
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    • Pages (749-756 )
    • No of Download = 681

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    This paper studies stress reduction effects induced on structures (such as bridge piers) due to basemat uplift and soil yielding by the use of a macro-element model for foundations placed on sand. A foundation-soil system is modeled as four cases; (1) fixed base, (2) elastic soil, (3) elastic soil with basemat uplift and (4) elasto-plastic soil with basemat uplift. Time histories with different frequency characteristics are considered as input motions to the models. Comparisons of responses of the models show a remarkable reduction of section force due to basemat uplift and soil yielding, depending on characteristics of input motions. Regarding the case where degree of stress reduction effect is largest, energy balance for the system is estimated. In this case, the input energy imparted to the structure by an earthquake tends to be reduced due to the effect of basemat uplift.

  2. IDENTIFICATION OF POLLUTANT SOURCE CHARACTERISTICS UNDER UNCERTAINTY IN CONTAMINATED WATER RESOURCES SYSTEMS USING ADAPTIVE SIMULATED ANEALING AND FUZZY LOGIC Download Article

    Mahsa Amirabdollahian and Bithin Datta
    • Article Type: Research Article
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    • Pages (757-762 )
    • No of Download = 640

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    Effective environmental management and remediation strategies are required to remediate contaminated water resources. Accurate characterizing of unknown contaminant sources is vital for selection of appropriate environmental management plan and reduction of long term remedial costs. In order to characterize the sources of contamination, the aquifer boundary conditions and hydrogeologic parameter values need to be estimated or specified. In real life contaminated aquifers, often there are sparse and inaccurate information available. On the other hand, extensive collection of data is very costly. The uncertain and highly variable natures of water resources systems affect the accuracy of contaminant source identification models. In this study, an optimal source identification model incorporating Adaptive Simulated Annealing optimization algorithm linked with the numerical flow and transport simulation models, is designed to identify contaminant source characteristics. The fuzzy logic concept is used to identify the effect of hydrogeological parameter uncertainty on groundwater flow and transport simulation. The fuzzy membership values incorporate the reliability of specified parameter values in to the optimization model. An illustrative study area is used to show the potential applicability of the proposed methodology. The incorporation of fuzzy logic in source identification model increases the applicability of contaminant source detection models in real-life contaminated water resources systems.

  3. EFFECT OF STIFFNESS OF THIN BEARING LAYER ON TOE BEARING MECHANISM OF STEEL PIPE PILE WITH A CONCRETE BULB Download Article

    Kazuhiro Oda, Shuhei Takegawa
    • Article Type: Research Article
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    • Pages (763-770 )
    • No of Download = 798

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    It has been known that the sufficiently stiff layer can be considered as a load-bearing layer of piles, even if its thickness is thin. The authors have studied the toe bearing resistance of pile on a thin load-bearing layer, in order to establish the design method about pile on a thin load-bearing layer. In this paper, the effect of stiffness of load-bearing layer on characteristics of toe resistance of steel pipe pile on a thin load-bearing layer is discussed through a series of numerical analyses. First, a field loading test of steel pipe piles with a concrete bulb on a thin load-bearing layer is reproduced through the numerical analysis, in which a soil-water coupled with an elast-plastic finite element method is applied, to confirm the availability of the numerical analysis proposed. Second, a series of numerical analyses are carried out in which the deformation modulus of the load-bearing layer and the thickness of load-bearing layer are chosen as a variable parameter. The results of the numerical analyses show that the stiffness of load-bearing layer affects the resistance when the yielding of load-bearing layer occurs.

  4. USE OF FULLY SOFTENED VERSUS PEAK STRENGTH TO PREDICT THE CAPACITY OF FOOTINGS ON GEOSYNTHETIC REINFORCED SOIL Download Article

    Melia K. Iwamoto, Phillip S.K. Ooi, Jennifer E. Nicks and Michael T. Adams
    • Article Type: Research Article
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    • Pages (771-778 )
    • No of Download = 501

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    A database of load tests performed on geosynthetic reinforced soil (GRS - reinforcement in this study is of the extensible variety) was developed using results of recent load tests performed on large scale GRS structures at the Federal Highway Administration’s Turner Fairbank Highway Research Center as well as results from the literature.  The measured capacities were compared to those predicted using the Wu and Pham [1] equation utilizing both the peak and fully softened soil shear strength parameters.  It was found that the fully softened strengths yielded capacities that agreed better with the measured capacities.  A rationale for this finding is that the robust reinforcement in a GRS strengthens the soil considerably causing the GRS to experience large strains prior to failure.  Because the soil peak strengths are mobilized at relatively small displacements/strains even in large scale direct shear or triaxial tests compared to the GRS load tests, it is postulated that the fully softened values are more appropriate to estimate the GRS bearing capacity.  A follow-on to this is that since large movements are required to fail say a GRS abutment, the design of GRS abutments will most likely be governed by the serviceability limit state rather than the ultimate limit state.

  5. ASSESSING REUSE OF AGRICULTURAL AND FOOD RESIDUES FOR NITRATE ATTENUATION IN POROUS MEDIA Download Article

    Kazuya Inoue, Saki Matsuyama and Tsutomu Tanaka
    • Article Type: Research Article
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    • Pages (779-784 )
    • No of Download = 716

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    Nitrate pollution in groundwater is related to surplus nitrate fertilizers and animal waste disposal. As high nitrate concentration leads to health concern, mass reduction of nitrate in a contaminated site is important. From the perspective of recent reuse streams, this paper assessed the potential of agricultural and food residues such as rice husk, rice straw and used coffee as a nitrate attenuation material in porous media. Under saturated flow conditions, column experiments were carried out in silica sand with a mixture of residues. KNO3 or NaCl solutions were injected into columns and were analyzed using temporal moment approaches to characterize the mobility of nitrate and chloride ions. The results showed that the mixture of rice straw leads to the increase of the retardation factor. The results also revealed that the use of rice husk and used coffee decreases the mass of both anions, whereas the rice straw has little effect on attenuation of these anions.

  6. OPTIMAL MONITORING NETWORK DESIGN FOR EFFICIENT IDENTIFICATION OF UNKNOWN GROUNDWATER POLLUTION SOURCES Download Article

    Om Prakash and Bithin Datta
    • Article Type: Research Article
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    • Pages (785-790 )
    • No of Download = 709

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    Application of linked simulation-optimization approach for solving groundwater identification problems is well established. Pollutant concentration measurements from different sets of monitoring locations, when used in a linked simulation-optimization approach, results in different degrees of accuracy of source identification. Moreover, the accuracy of source identification results depends on the number and spatiotemporal locations of pollutant concentrations measurements. This study aims at improving the accuracy of source identification results, by using concentration measurements from an optimally designed monitoring network. A linked simulation optimization based methodology is used for optimal source identification. Genetic programming based impact factor is used for designing the optimal monitoring network. Concentration measurement data from the designed network is then used, in the Simulated Annealing based linked simulation-optimization model for efficient source identification. The potential application of the developed methodology is demonstrated by evaluating its performance for an illustrative study area. These performance evaluation results show improvement in the efficiency in source identification when such designed monitoring networks are utilized.

  7. PURIFICATION SYSTEM OF OCEAN SLUDGE BY ACTIVATING MICROORGANISMS Download Article

    Kyoichi Okamoto, Kenji Hotta, Takeshi Toyama and Hideki Kohno
    • Article Type: Research Article
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    • Pages (791-795 )
    • No of Download = 864

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    Ocean sludge exerts a very big environmental load to local sea area. Here, attention was paid to micro-bubble technology for application to the purification of sludge. The important point in this technique is to activate the bacteria existing in the area by micro-bubbles. We had developed a method for decomposing the sludge by using of microorganisms in an aerobic state by micro-bubble. In this study, our objects are to develop a new powerful purification system for sedimentary sludge using a micro-bubble device and by activating microorganism. As the results of our experiments, we succeeded in reducing the time needed to purify the sludge.

  8. X-RAY IMAGE ANALYSIS OF POROSITY OF PERVIOUS CONCRETES Download Article

    Jaehun Ahn, Jinwoo Jung, Seungbae Kim and Shin-In Han
    • Article Type: Research Article
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    • Pages (796-799 )
    • No of Download = 875

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    The use of permeable pavement is one of the most promising tools to control runoff and water quality, therefore enabling low impact development (LID), along with several other benefits. The porosity of the permeable pavement is the most important property of the pavement in current state of the practice. In this article, the porosity of a pervious concrete sample made in laboratory was evaluated by two approaches: measuring weights and X-ray image analysis. Two different X-ray imaging apparatus, 2D and 3D, were used to construct cross-sectional planar images of a cylindrical pervious concrete sample. It was found that the porosity estimate from 2D X-ray was close to the results with measuring weights, but that of 3D X-ray was rather larger under X-ray imaging configuration and image analysis technique used. The viability of using X-ray images to evaluate the pore characteristics of permeable pavement, and future applications are discussed.

  9. STABILITY OF A ROCK SLOPE SUSCEPTIBLE TO SEASONAL MOVEMENTS Download Article

    A. K. Alzo’ubi
    • Article Type: Research Article
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    • Pages (800-805 )
    • No of Download = 576

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    A rock slope, known as the Checkerboard Creek slope located in British Columbia, Canada, is moving under the effect of seasonal temperature changes. Freezing and thawing processes are causing the rock to move at rate of 13 mm/year. A 60 m deep weathered zone has been identified along the slope. This paper uses a discrete element numerical modeling approach to investigate the Checkerboard Creek slope, which is moving toward the reservoir, and to propose a support system to stabilize the slope. The numerical simulation conducted in this study shows that the failure is situated near the slope’s toe where a road-cut has been made. To stabilize the rock slope, a support system comprising of cables and a shotcrete layer was proposed and installed numerically along the steepest portion of the weathered rock area. Comparison studies showed that the proposed support system could successfully stabilize the moving rock slope at a reduced tensile strength value. By using this support system, the risk of rock slope failure will be reduced to an acceptable limit through increasing the Factor of Safety of the slope to 1.15. Installing a support system for this problematic slope is highly recommended.

  10. A STUDY OF PILE DRIVING EFFECTS ON NEARBY BUILDING Download Article

    Adhilla Ainun Musir and Abdul Naser Abdul Ghani
    • Article Type: Research Article
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    • Pages (806-810 )
    • No of Download = 672

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    Piles are used to support many major structures such as buildings and bridges. It is known that pile driving activity creates vibrations in the ground and may affect nearby building and structure. However, the different pile size and shape as well as installation distances factors remain as interesting subjects for studies. The effect of hammer driven piles installation were studied using laboratory scale model. Three main effects were studied in which they are the response on top and bottom of a building, the vibration creates by three different distances of driven pile and the vibration produced by two different pile sizes. It can be concluded that the effect of vibrations are higher at the bottom of the building. The result also indicated that the nearest distance of piling activity produced higher vibration. However, it is interesting to note that the smaller pile creates larger vibrations

  11. INFLUENCE OF THE SOIL-STRUCTURE INTERACTION ON THE SEISMIC BEHAVIOR OF BUILDINGS ON SHALLOW FOUNDATIONS Download Article

    Z. Benadla, K. Hamdaoui, S. Aissaoui and A. Baouch
    • Article Type: Research Article
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    • Pages (811-816 )
    • No of Download = 739

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    The objective of this work is to study the mobility of shallow foundations relative to the subgrade by considering two cases. In the first, the structure is fixed at its base. For the second, the foundation is replaced by hinges and springs, where their stiffnesses are expressed in terms of the geometry of the foundation and soil shear strength. The comparison is made on a dynamic model when the two tested cases are confronted. Thereafter, a parametric study is considered to see the effect of all the parameters that can play a key role in the structural response. Then, these results will be validated on real structure cases, by considering important Algerian earthquakes: the one of Aïn Témouchent in 1999 and the earthquake of Boumerdès in 2003. The extracted results will permit to make the point on all the elements that may influence the seismic response of buildings while considering the interface soil-foundation-structure.

  12. LABORATORY EVALUATION OF PHYSICO-CHEMICAL VARIATIONS IN BENTONITE UNDER ELECTROKINETIC ENHANCEMENT Download Article

    Nasim Mosavat, Erwin Oh and Gary Chai
    • Article Type: Research Article
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    • Pages (817-823 )
    • No of Download = 802

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    When the traditional ground improvement techniques are not practical for a particular situation, alternative technology, such as electrokinetic (EK) soil treatment can be considered. EK treatment method involves applying a low direct current (DC) or a low potential gradient to arrays of electrodes inserted in the low permeable soils simulating migration of electricity, pore water, ions and charged particles across the soil, hence modifying the physicochemical, mechanical and engineering properties of the soil. This study investigates the effects of EK treatment on conductance phenomena and physico-chemical changes of bentonite at different intervals under total applied voltage of 10V subjected to specific types of anode enhancement solutions. The cumulative electroosmotic flow and electric current through the sample was measured for 15 days of treatment. The specimens were also tested for moisture content, pH and undrained shear strength variations over different time periods of 3, 6, 9, 12 and 15 days showing good correlations between the soil parameters.

  13. STATISTICAL EVALUATION OF EMBEDMENT EFFECT ON DAMAGE TO BUILDING STRUCTURES BASED ON DATA FROM THE 1995 HYOGOKEN-NANBU EARTHQUAKE Download Article

    Atsushi Mikami
    • Article Type: Research Article
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    • Pages (824-831 )
    • No of Download = 621

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    In the 1995 Hyogoken-Nanbu Earthquake, a lot of building structures were severely damaged, and valuable data was compiled after the investigation by the Architectural Institute of Japan (AIJ).  This study statistically evaluates effect of embedment due to presence of basements on damage mitigation of reinforced concrete (RC) building structures based on building damage data from the 1995 Hyogoken-Nanbu Earthquake. A multivariate analysis (Hayashi’s Quantification II) is used to investigate factors (items) that have a strong effect on the degree of damage to RC buildings.  The results indicate that embedment has a remarkable effect on reducing damage; the degree of which is similar to the construction year effect (due to major revision of Japanese building standard law that became effective in 1981).  This finding may support further positive adoption of embedment effect in seismic design practice.